Abstract: The development of cognitive skills often involves a transition from an effortful and slow rule-based process to a more fluent memory retrieval process, which occurs with repeated practice on relevant problems (Ackerman & Woltz, 1994; Logan, 1988; Rickard, 1997). As task discriminations become more familiar with practice, individuals can respond quickly and accurately on the basis of remembering the answers rather than having to compute them. In many current models of skill acquisition, transition to retrieval-based processing involves a parallel race between algorithm and memory retrieval (e.g., Logan, 1988; Nosfsky & Palmeri, 1997; Palmeri, 1999); in other models a fast, early strategy choice (algorithm vs. retrieval) is involved (Rickard, 1997, 2004) prior to retrieval of the correct solution (e.g., Reder & Ritter, 1992; Schunn, Reder, Nhouyvanisvong, Richards, & Stroffolino, 1997). In all these models, the rate of associative learning is a key factor in determining whether the problem is solved by retrieval versus algorithm. As items become better learned, the fluency of memory retrieval in accessing the solution increases, as does the fluency of a fast familiarity mechanism for problem recognition that is thought to be a principal influence on early strategic choice.